STMicroelectronics TL431IDT

Overview

TL431IDT from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference with 2% initial voltage accuracy, operating across –40 °C to +105 °C, delivering 2.5–36 V output via two external resistors, sinking 1–100 mA, and featuring 0.22 Ω typical dynamic impedance - used in feedback loops of isolated DC-DC converters and battery management systems.

For engineers reviewing the TL431IDT datasheet, TL431IDT pinout, TL431IDT application, or TL431IDT equivalent, this page delivers verified circuit role (precision shunt reference), thermal range compliance (automotive), sink current capability, dynamic impedance, and SO-8 package mapping - all confirmed from ST's production datasheet DocID4467 Rev 17.

Technical Context

The TL431IDT implements a precision bandgap-based reference amplifier driving an NPN transistor output stage in shunt configuration. Its internal 2.5 V reference is compared against a user-defined resistor divider at the REF pin, enabling programmable output voltage regulation independent of cathode-anode voltage up to 36 V.

It operates over a wide cathode current range (1–100 mA) with guaranteed stability under capacitive loads and maintains 2% voltage tolerance across its full automotive temperature range (–40 °C to +105 °C), supported by 0.22 Ω typical dynamic impedance and <1 µA reference input current.

Key Specifications

Pinout & Package

TL431IDT is supplied in SO-8 "batwing" plastic micropackage (ECOPACK® compliant), offering enhanced thermal performance (R_thJA = 85 °C/W) and mechanical robustness for automotive PCB assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable shunt reference applications.

Compared with TL431IDT, TL431ACDT offers improved accuracy at identical thermal rating, while TL431BIDT extends temperature range and tightens tolerance - both retain pin compatibility and SO-8 footprint but require validation of reference current and dynamic impedance in high-frequency feedback loops.

Availability

TL431IDT is available at Aetrix Electronics and suitable for automotive power supplies, industrial DC-DC converters, and battery management systems requiring stable component supply with AEC-Q100 traceability and SO-8 thermal performance.

Supply support for TL431IDT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and automotive ICs for industrial and automotive markets.

TL431IDT belongs to ST's precision voltage reference product line, engineered specifically for automotive-grade feedback regulation in isolated power converters and safety-critical subsystems.

FAQ

What is the maximum cathode-anode voltage for TL431IDT?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V, with continuous operation specified up to 36 V. Exceeding 36 V risks degradation of regulation accuracy and long-term reliability, especially at elevated temperatures. This rating enables direct use in 24 V automotive systems and 36 V industrial buses without external clamping.

Can TL431IDT replace TL431CDT in existing designs?

Yes, TL431IDT is a direct drop-in replacement for TL431CDT in terms of pinout and SO-8 package, but it extends the operating temperature range from 0 °C to +70 °C (CDT) to –40 °C to +105 °C (IDT) and maintains the same 2% accuracy. No layout change is needed, though thermal derating should be rechecked for high-ambient applications.

How does the REF pin function in TL431IDT?

REF is a high-impedance input (≤4 µA max) that compares the external resistor-divider voltage against the internal 2.5 V bandgap reference. When the divider voltage equals 2.5 V, the device regulates; deviation triggers proportional cathode current adjustment. It must be driven only by passive resistive dividers - not active circuitry - to avoid instability.

Is TL431IDT suitable for use with optocouplers in flyback converters?

Yes - TL431IDT is widely deployed in secondary-side regulation of flyback converters driving PC817 or SFH615A optocouplers. Its 1–100 mA sink capability directly biases the optocoupler LED, and its 0.22 Ω dynamic impedance ensures minimal output voltage deviation during transient load changes, maintaining tight cross-regulation.